Experimental group B streptococcal infections in mice: hematogenous virulence and mucosal colonization

Abstract

A group B streptococcus recovered from a blood specimen from a neonate with sepsis was used to evaluate the use of mice for studies characterizing the hematogenous virulence and the asymptomatic mucosal colonization of the vagina or of the respiratory tract by these bacteria. When injected intravenously, the 50% lethal dose for mice was 106; however, as few as 102 organisms produced septic deaths. In mice undergoing water diuresis, bacteriuria and pyelonephritis were not produced after direct bladder inoculation of the streptococci. Asymptomatic vaginal colonizations that persisted for 12 days were produced in both pregnant and virgin mice. Vaginal colonization before delivery did not result in transmission of infection to litters or in protection against subsequent oropharyngeal colonization in the suckling mice. In mice born of nonexposed mothers, oropharyngeal colonization was produced in both suckling and 3week-old weaned mice. Whereas infection persisted for 14 days in all suckling mice, clearance occurred in over 50% of the weaned mice by day 14. The use of mice for studies on the virulence of the group B streptococci as well as for studies on the pathogenesis of disease by virulent strains is discussed.

Protective effect of Group B Streptococcus type-III polysaccharide conjugates against maternal colonization, ascending infection and neonatal transmission in rodent models

“…Animal models of vaginal colonization have been developed with three main aims: investigating GBS factors involved in host interaction that may favor bacterial acquisition and persistence 11 – 14 , elucidating host innate immune responses 13 , 15 and identifying potential preventive strategies 16 – 18 . By these models, it has been demonstrated that GBS carriage induces infiltration of lymphocytes and the production of soluble inflammatory mediators in the vaginal mucosa, and that GBS bacteria can persist in the genital tract for long periods by subverting innate immune defenses.…”

Effects of route and time of administration of antiserum on protection of mice from lethal infection due to group B Streptococcus type III

“…Numerous studies have successfully employed the mouse lethality test as a model for study of disease due to GBS (7,9,11,14,16). However, certain parameters of the model have not yet been delineated.…”

“…Antibody to GBS has been detected by functional assays of immunity which include opsonization (1, 6, 10, 12, 14,), chicken embryo protection (15), and mouse protection tests (7,11,14). Several authors have described the similarity of the pathology of GBS infection of mice to that of humans (9,16). Until recently, the mouse model had been utilized only for the study of GBS serotypes Ia, Ib, Ic, and II because of the inability to cause lethal disease in mice with serotype III strains (2,14,15).…”

Experimental vaginal colonization and mother-infant transmission of group B streptococci in rats

“…In the study of the pathogenesis of this disease, several animal models have been developed. These include a chicken embryo model (20), an adult mouse model (22), a newborn mouse model (10), and a newborn rat model (7,9). The design of these models allows the study of the natural history, progression, and pathology of group B streptococcal disease but gives limited information concerning its epidemiology.…”

“…The design of these models allows the study of the natural history, progression, and pathology of group B streptococcal disease but gives limited information concerning its epidemiology. The mouse model described by Furtado (10) demonstrated that group B streptococci could colonize mucosal surfaces, such as vagina and pharynx, of these rodents, but there was no investigation of neonatal acquisition (in contrast to disease) or of mother-infant transmission of group B streptococci.…”